Explosion pressure gauge



Aug, 24

SKMMQNS, 2

EXPLOSION PRESSURE GAUGE Original Filed Feb. 25 1940 Patented Aug. 2%, l3

r en it are cressure .c g suclclenucssq have en plot ell me rsriicsl as Well other ve not been suirlclently for ordin-rv an object of invention to prcvitle an proved appcratus for fluid press e with a high of accuracy, sensitivity and ciepentlahllitv combined with simplicity, economy of construction, operation and maintehence, es well rugged.

A further object of my invention is to provide en improved finial pressure measuring apparatus suficientlv compact c1 simple so that it mav be easily insert-eel within a relatively small opening in the wall of a chamber in which a sudden fluid pressure may be measured.

Other objects and "antages will be more apparent to those skilled in the art from the following description of the accompanying drawing which is a sectional view through my improved apparatus.

Some present high speed engine indicator gauges use a piezo=electric strain sensitive system but are objectlonal because of leakage of electrical charge and therefore not applicable to slowly changing or static pressure measurement. A second objection is their temperature limitation. My improved apparatus employs a. strain sensitive filament which, when applied to a piston-like pressure element described below, is free of the first objection stated above and secondly is capable of withstanding much higher temperatures than piece-electric gauges. In my apparatus the strain sensitive filament 81 is attached to a dynamometer stud 88, preferably enlarges. ar

i so as not clistu vesse ans. it may be easily pee erature epplicaticns, new is evaporated on. the .e rometer stud tc serve as erllunl between. the Wire and the ""e cement or fusible glass element throughout its v length to clviuamometer stud. the

seine around the clgmamometer stud and connected as one em: of a Wheetstone r measuring changes in resistance in in response to compressive strains therein by the expansion of stud 88 when u pressure terse impinges upon piston 880:, the piston losing axially movable in cylinder 88b to permit said compressible strain. Parts cs prevent accumulation of pressure behind head 880:. The Wheatstone bridge for measuring changes in resistance of the filament is well-known aml is more fully described in my copending applicatlon. $erlal No. 320,327, filed February 23, 1940 new Patent No, 22%,549, issued April 11, 1942, of which the present application is a division.

As disclosed in said parent application, the filament consists of a very fine metallic wire continuously solid throughout its length and whose electrical strain characteristics are predetermined. This wire may be of suitable and wellknown material such as constantan, advance and various other well-known materials having good resistance properties as well as being capable of fabrication in small wire sizes. I have employed filaments approximately 0.001 to 0.003 of an inch in diameter. The strain filament emplays the well-known principle that the electrical resistance of materials varies with the strain thereof, herein referred to as electrical strain sensitivity. The filament is bonded throughout its efiectlve length to the surface subject to strain by suitable bonding and electrical insulating material such as glypta although in the specific embodiment 01' my engine indicator where high temperature may be encountered I employ, as above described, a high temperature fusible glass to attach to the filament to the dynamometer.

From the foregoing disclosure, it is seen that I have provided a pressure indicator that is simple, compact and relatively inexpensive in construction, operation and maintenance, and yet has a high degree of sensitivity, accuracy and responsiveness thereby producing a very eifective pressure indicating device that is especially applicable for measuring sudden explosive forces.

It will of course be understood that various changes in details of construction and arrangement of parts may be made by those skilled in the art without departing from the spirit of the invention as set forth in the appended claims.

I claim:

1. A pressure responsive apparatus comprising, in combination, a member having a bore subject to fluid pressure at one end, a dynamorneter stud disposed in said bore and having a front end and a rear end, said rear end of the stud being held against movement in said bore while said front end of the stud has a sliding fit in said bore and is adapted to have axial movement in response to a fluid pressure force applied thereto from the end of the bore subject to pressure, said stud having a peripheral portion subject to strain in response to said axial movement, and a continuous solid filament of electrical conducting material bonded throughout its effective length to' said peripheral portion of the dynamometer stud and whose electrical resistance varies with its strain whereby the resistance of said filament is responsive to strains in said stud arising from 3. The combination set forth in claim 1 furthercharacterized in that said stud has an enlarged head axially movable within said bore and being substantially flush with the end thereof whereby said head constitutes the fluid pressure end of the stud while said peripheral portion is located rearwardly of said enlarged head.

4. A pressure responsive apparatus comprising, in combination, a member insertable in an opening formed in the wall of a pressure vessel, said member having a bore open at its inner end adjacent said wall and closed at its outer end, a dynamometer stud having a reduced intermediate portion thereby forming enlarged ends on the stud one of which is seated in the closed end of said bore and the other of which is slidably disposed in said bore near the inner end thereof so as to be exposed to pressure within the pressure vessel, and a continuous so id filament of electrical conducting material bonded throughout its efiective length on the surface of said reduced portion and whose electrical resistance varies with its strain whereby the resistance of said filament is responsive to strains in said stud created by fluid pressure forces on the exposed enlarged end of said dynamometer.

EDWARD E. SIMMONS, JR. 

